Twist beam axles are configured as part of the wheel suspension of a vehicle, generally as the rear axle. In particular, in motor vehicles they are often combined with a front wheel drive acting on the front wheels. The construction thereof provides two longitudinal rocker arms on which one respective wheel of the vehicle axle is rotatably arranged. The longitudinal rocker arms are connected together in a flexurally rigid manner transversely to a longitudinal axis of the vehicle which lies in the direction of travel of the vehicle. The torsion profile is distorted during the deflection and rebound of one of the longitudinal rocker arms. This permits the simple structural design of a vehicle axle. In this case, the torsion profile simultaneously serves as a transverse anti-roll bar.
The coupling of such a twist beam axle to the structure of a vehicle is implemented by two bearing arrangements. The bearing arrangements are spaced apart from one another in the longitudinal direction of the torsion profile and are generally configured as rubber metal bearings or contain such bearings. The bearing arrangements form a structural rotational axis about which the respective longitudinal rocker arm is able to be pivoted on the vehicle structure.
In order to maintain the required characteristic, generally open hollow cross sections are used as the torsion profile. The open hollow cross sections permit easier rotatability around their respective longitudinal direction relative to closed hollow profiles. Due to the additional function as a transverse anti-roll bar, the design of the torsion profile has considerable influence on the rolling behavior of a vehicle thus equipped. “Rolling” means the tendency of a vehicle to tilt out of the corner when cornering due to the centrifugal force.
Typically, the torsional rigidity of the base body of such a torsion profile may be adjusted by altering its material thickness. This means that the torsional rigidity increases with increasing material thickness. A drawback here is that the weight also increases with increasing material thickness. This also is relevant to the driving safety and driving comfort, as this is an unsprung mass.
Alternatively or in addition, the arrangement of recessed or stamped-out openings through the wall of the base body, for example in the form of holes, has been used to reduce weight around the correspondingly recessed regions. However, the result of such measures is that the stress paths inside the torsion profile may disadvantageously change. In this case it is, in particular, the stresses caused by such openings which are able to concentrate on the edges of the openings. As a result, the risk of possible crack formation is correspondingly increased.
Based on these structures, it is clear that torsion profiles and, in particular, twist beam axles comprising such torsion profiles can be further improved.